The man who brought through the likes of David Beckham, Paul Scholes, Ryan Giggs, the Neville brothers and Nicky Butt is well aware that City are now mixing it with United due to their big-spending ways but hopes that they can still produce some homegrown players otherwise it will a short-lived time at the top.
"Sir Alex has said this week that this is the biggest Manchester derby in his time at the club and he is right," he said.
"Everybody at the football club now recognises City as a real threat. They are a very, very talented team.
In regards to developing youngsters, Harrison indicated that City would lose out if they went away from that nurturing way which United have excelled at in recent years.
"That would be very, very sad. When any young player goes to a football club their aim must is to make it into the first team," he added.
"There is the temptation to buy someone ready-made but if that means young players are blocked, it is a real tragedy.
"At United progressing youth players is part and parcel of the club. I know that when Sir Alex eventually decides it is time to go upstairs, a large part of the interviews for the candidates to replace him will concern their plans for how to keep the development of youth players going."